AMOUNT OF PRACTICE: ADDITION BONDS IN A RECENT TEXTBOOK (A) OF EXCELLENT REPUTE. BOOKS I AND II, ALL SAVE FOUR SECTIONS OF SUPPLEMENTARY MATERIAL, TO BE USED AT THE TEACHER'S DISCRETION The Table reads: 2 + 2 was used 226 times, 12 + 2 was used 74 times, 22 + 2, 32 + 2, 42 + 2, and so on were used 50 times. ====================================================================== | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | TOTAL ----------------+-----+-----+-----+-----+-----+-----+-----+----+------ 2 | 226 | 154 | 162 | 150 | 97 | 87 | 66 | 45| 12 | 74 | 53 | 76 | 46 | 51 | 37 | 36 | 33| 22, etc. | 50 | 60 | 68 | 63 | 42 | 50 | 38 | 26| | | | | | | | | | 3 | 216 | 141 | 127 | 89 | 82 | 54 | 58 | 40| 13 | 43 | 43 | 60 | 70 | 52 | 30 | 22 | 18| 23, etc. | 15 | 30 | 51 | 50 | 42 | 32 | 29 | 30| | | | | | | | | | 7 | 85 | 90 | 103 | 103 | 84 | 81 | 61 | 47| 17 | 35 | 25 | 42 | 32 | 35 | 21 | 29 | 16| 27, etc. | 30 | 23 | 32 | 29 | 24 | 23 | 25 | 28| | | | | | | | | | 8 | 185 | 112 | 146 | 99 | 75 | 71 | 73 | 61| 18 | 28 | 35 | 52 | 46 | 28 | 29 | 24 | 14| 28, etc. | 53 | 36 | 34 | 38 | 23 | 36 | 27 | 27| | | | | | | | | | 9 | 104 | 81 | 112 | 96 | 63 | 74 | 58 | 57| 19 | 13 | 11 | 31 | 38 | 25 | 14 | 22 | 11| 29, etc. | 19 | 17 | 27 | 20 | 32 | 32 | 19 | 18| | | | | | | | | | 2, 12, 22, etc. | 350 | 277 | 306 | 260 | 190 | 174 | 140 | 104| 1801 3, 13, 23, etc. | 274 | 214 | 230 | 209 | 176 | 116 | 109 | 88| 1406 | | | | | | | | | 7, 17, 27, etc. | 148 | 138 | 187 | 164 | 141 | 125 | 115 | 91| 1109 8, 18, 28, etc. | 266 | 183 | 232 | 185 | 126 | 136 | 124 | 102| 1354 9, 19, 29, etc. | 136 | 109 | 170 | 154 | 120 | 120 | 99 | 86| 994 | | | | | | | | | Totals |1164 | 921 |1125 | 972 | 753 | 671 | 687 | 471| ====================================================================== TABLE 4 AMOUNT OF PRACTICE: SUBTRACTION BONDS IN A RECENT TEXTBOOK (A) OF EXCELLENT REPUTE. BOOKS I AND II, ALL SAVE FOUR SECTIONS OF SUPPLEMENTARY MATERIAL, TO BE USED AT THE TEACHER'S DISCRETION